Simulation of summer-time diurnal bacterial dynamics in the atmospheric surface layer

A model was prepared to simulate the observed concentration dynamics of culturable bacteria in the diurnal summer atmosphere at a Willamette River Valley, Oregon location. The meteorological and bacterial mechanisms included in a dynamic null-dimensional model with one-second time step are solar radiation, convective mixed layer depth, bacterial concentration in the residual layer, bacterial flux from ground sources, and SR sensitivity of two bacterial populations. Reasonable agreement of the model to observed airborne bacterial concentration data was found for the dawn fumigation and afternoon accumulation peaks where the activating mechanisms were included in the model. But little agreement was found in the late afternoon where unaccounted-for mechanisms of bacteria-sparse seabreeze intrusion and downslope mountain movement of airmasses are thought to be present at the observation location.